July 2020

Lithium-ion batteries have received considerable attention due to the increasing demand for electrochemical energy storage. However, commercial lithium-ion batteries suffer from severe safety concerns stemming from the organic liquid electrolyte (e.g., they are flammable). Solid-state batteries (SSBs) are expected to be a promising candidate complementing batteries with organic liquid electrolyte. Nevertheless, the development of SSBs still faces considerable challenges hindering their full-scale commercialization. One of the major issues is the high charge-transfer resistance between the electrode materials and the solid electrolyte due side reactions at the electrode/electrolyte interface. Therefore, the WG Schröder and the WG Janek investigate the underlying degradation processes in SSBs. In detail, we examine the degradation reactions at the interface of various composite cathode materials and ceramic solid electrolytes within the GER-JPN-joint BMBF-project InCa. The SEM image displays the interface between composite cathode and solid electrolyte, and the graphic schematically illustrates the degradation process. Impedance measurements were carried out to monitor the evolution of the degradation layer between the compounds. A characteristic frequency (~200 – 500 Hz), which can be ascribed to the degradation processes at the interface, is indicated in the Nyquist plot. Thereby, the gradually increasing resistance between composite cathode and solid electrolyte are mainly caused by the growing degradation layer. (Picture submitted by TongTong Zuo and Daniel Schröder).